"""当前 Windows Client 身份的本地保存与读取服务。"""

import hashlib
import platform
import uuid
from dataclasses import dataclass
from typing import Callable, Optional

from .settings_repository import SettingsRepository


CLIENT_ID_KEY = "admin.client_id"
CLIENT_NAME_KEY = "admin.client_name"


def generate_client_device_id() -> str:
    """根据本机特征生成稳定设备号，只保留不可逆哈希。"""

    fingerprint = "|".join(
        (
            platform.system(),
            platform.node(),
            platform.machine(),
            f"{uuid.getnode():012x}",
        )
    )
    digest = hashlib.sha256(fingerprint.encode("utf-8")).hexdigest()[:16]
    return f"CLIENT-{digest.upper()}"


@dataclass(frozen=True)
class CurrentClientSettings:
    """本地已经确认保存的当前 Client 信息。"""

    client_id: str
    client_name: str


class CurrentClientService:
    """保证设备号只生成一次，并与名称一起原子保存。"""

    def __init__(
        self,
        repository: SettingsRepository,
        device_id_factory: Callable[[], str] = generate_client_device_id,
    ):
        self._repository = repository
        self._device_id_factory = device_id_factory

    def load(self) -> CurrentClientSettings:
        """读取已保存的信息；缺少的字段返回空字符串。"""

        client_id = self._clean_text(self._repository.get(CLIENT_ID_KEY, ""))
        client_name = self._clean_text(
            self._repository.get(CLIENT_NAME_KEY, "")
        )
        return CurrentClientSettings(client_id, client_name)

    def save(self, client_name: str) -> CurrentClientSettings:
        """保存名称；设备号不存在时生成，存在时保持不变。"""

        normalized_name = self._clean_text(client_name)
        if len(normalized_name) > 50:
            raise ValueError("设备名最多 50 个字")

        existing = self.load()
        client_id = existing.client_id
        if not client_id:
            client_id = self._clean_text(self._device_id_factory())
            if not client_id:
                raise ValueError("生成的设备号不能为空")

        self._repository.set_many(
            {
                CLIENT_ID_KEY: client_id,
                CLIENT_NAME_KEY: normalized_name,
            }
        )
        return CurrentClientSettings(client_id, normalized_name)

    @staticmethod
    def _clean_text(value: object) -> str:
        return value.strip() if isinstance(value, str) else ""